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  Disk recording apparatus, method, and recording control programUSPTO Application #: 20060233066Title: Disk recording apparatus, method, and recording control program Abstract: An optical disk recording apparatus includes a beam emitting unit operable to emit a first beam for irradiating a track on an optical disk so as to record data and second and third beams for irradiating spaces between the track and tracks on both sides of the track, respectively; a light detection mechanism operable to detect the first to third beams reflected from the optical disk; a tracking controller operable to control tracking of the first beam on the basis of results of the reflected first to third beams detected by the light detection mechanism; and a determination unit operable to determine whether the first beam records data on a white portion of the track or overwrites data on a recorded portion of the track based on changes in reflected light amounts of the second and third beams detected by the light detection mechanism. (end of abstract) Agent: Lerner, David, Littenberg, Krumholz & Mentlik - Westfield, NJ, US Inventor: Nobuhiko Ando USPTO Applicaton #: 20060233066 - Class: 369044110 (USPTO) Related Patent Categories: Dynamic Information Storage Or Retrieval, With Servo Positioning Of Transducer Assembly Over Track Combined With Information Signal Processing, Optical Servo System The Patent Description & Claims data below is from USPTO Patent Application 20060233066. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority from Japanese Patent Application No. JP 2005-086547 filed on Mar. 24, 2005, the disclosure of which is hereby incorporated by reference herein. BACKGROUND OF THE INVENTION [0002] The present invention relates to a disk recording apparatus, a recording method, and a recording control program suitable for use in recording data by tracking control of an optical disk having multiple recording layers using a DPP (differential push-pull) system. [0003] Recently, recordable optical disks have been generally used as recording media for recording digital data. For example, in standards of CDs (compact disc) and DVDs (digital versatile disc), recordable optical disks are defined. In particular, the recordable DVD can store high-capacity data, so that it has been significantly in wide spread use as a recording medium replaceable from a conventional magnetic tape. Also, a recordable DVD with two recording layers capable of recording much higher capacity data has appeared. [0004] In a one side two-layered disk having two recording layers on one side, the two recording layers are respectively referred to as an L0 layer and an L1 layer from the incident side of laser light in that order. For example, in "DVD+R" standard, the L0 layer is accessed toward the outer periphery of the disk from the inner periphery in the same way as in a single layered disk while the L1 layer is accessed toward the inner periphery of the disk from the outer periphery. Thereby, the L1 layer can be easily accessed continuously from the L0 layer. [0005] In recordable DVDs, there are a write once DVD and a rewritable DVD rewritable data recorded before. The rewritable DVD will be described below unless otherwise specified. Rewritable DVD standards include a DVD-RW standard, a DVD+RW standard, and a DVD-RAM (random access memory) standard. The DVD-RW standard and the DVD+RW standard will be described below. [0006] In such a rewritable optical disk, a tracking error signal is detected so as to take tracking using a groove provided in the disk, and pits are formed on the groove by a laser beam emitted from an optical pick-up so that data are recorded by forming a track with a pit train. [0007] In the rewritable optical disk complying with DVD-RW standards and DVD+RW standards, the tracking error signal may be detected by a DPP (differential push-pull) system. A tracking control technique by the DPP system is disclosed in Japanese Unexamined Patent Application Publication No. 2005-25790. [0008] In the DPP system, a laser beam emitted from a laser diode is divided into a zero-order beam (main beam) and two first-order beams (side beams) using a diffraction grating. The three divided beams are arranged such that when the main beam is positioned on the groove, the two side beams are located on lands on both sides, respectively. The reflected beams from the respective beams of the optical disk are detected by a split-half light detector, respectively, so as to have a push-pull signal, and then, a tracking error signal DPP is obtained by the computation using equation (1). According to the DPP system, a satisfactory tracking error signal DPP can be obtained without being affected by the visual field deviation in an object lens of the optical pick-up. DPP=mpp-G.times.(spp.sub.1+spp.sub.2) (1) mpp: push-pull signal of the main beam spp.sub.1, spp.sub.2: push-pull signals of the two side beams G: a gain defined by the light quantity of the side beam and the gain of a photo-detector (DPP gain) [0009] The push-pull signal is the difference between detected signals of the split-half light-receiving surfaces of the split-half light detector. A tracking servo moves the beams so as to be PD1=PD2 for tracking. That is, the tracking servo moves the beams so as to be the tracking error signal DPP=zero in the above equation (1). [0010] FIG. 20 shows an example of the arrangement of the main beam and the two side beams on an optical disk 100 according to the DPP system. Referring to FIG. 20, the rotation direction of the optical disk 100 is assumed to be clockwise, and the optical disk 100 is provided with grooves 101, 101, . . . formed roughly concentrically about the disk center in advance. Between the grooves 101 and 101, a land 102 is formed. The grooves 101, 101, . . . meander slightly in fact; however, they are shown by straight lines in FIG. 20. [0011] Two side beams 103A and 103B are arranged in front and in rear of a main beam 104 in the rotation direction of the optical disk 100, respectively. In general, the side beam 103A, which is positioned in front of the main beam 104 in the rotation direction, is arranged in the outer radial side than the main beam 104, while the side beam 103B, which is positioned in rear of the main beam 104 in the rotation direction, is arranged in the inner radial side than the main beam 104. Hence, when recording from the inner radial side of the disk toward the outer radial side, the side beam 103A precedes the main beam 104 while the side beam 103B succeeds the main beam 104. [0012] When data is recorded on a white area of the optical disk 100, a track, through which the main beam 104 has passed, is the recorded track already having a pit formed thereon while a track preceding the main beam 104 is a white track having no pit yet. The white track generally has a reflectance of laser light higher than that of the recorded track. [0013] Accordingly, as shown in FIG. 21, in the side beam 103A for example, if one side track of the beam is a white track and the other side track is a recorded track, even when the main beam 104 is positioned at the center of the track, the respective photo-acceptance amounts due to the side beam 103A on the split-half light-receiving surfaces of the split-half light detector differ from each other. In the state of FIG. 21, the photo-acceptance amount PD.sub.1 on the split-half light-receiving surface on the white track side of the split-half light detector is larger than that on the split-half light-receiving surface PD.sub.2 on the recorded track side. As a result, the push-pull signal output from the split-half light detector has an offset. [0014] As described above, the tracking servo moves the beams so that the difference between detected signals due to the split-half light-receiving surfaces PD1 and PD2 of the split-half light detector becomes zero. Thus, in the example of FIG. 21, the tracking servo is operated so that the beam is moved toward the recorded track. As a result, the main beam deviates from the track so as to be de-tracking. The de-tracking is designated that although the main beam can trace the track, it deviates from the track center. [0015] The recording on the white track is referred to as a DOW (Direct Over Write) 0 while the recording on the recorded track is referred to as a DOW1. [0016] When the side beam 103A, which is positioned in front of the main beam 104 in the rotation direction of the disk, is arranged in the outer radial side than the main beam 104, a case where the L0 layer of a single-layered disk or the one side two-layered disk is recorded will be considered. In this case, the recording is executed from the inner radial side of the optical disk 100 toward the outer radial side. When recording on the white track (DOW0 state), as shown in FIG. 22A, tracks on both sides of the side beam 103A are white while tracks on both sides of the side beam 103B are already recorded. Since the respective both sides of the side beam 103A and the side beam 103B are in the same states, the difference between photo-acceptance amounts of the split-half light-receiving surfaces of the split-half light detector is small so that push-pull signals spp1 and spp2 of the side beam 103A and the side beam 103B have no offset. Accordingly, when the beam is moved so as to be the tracking error signal DPP=zero, the main beam may not be detracked. [0017] Similarly, when the L0 layer of the single-layered disk or the one side two-layered disk is recorded, in the state that the recorded track is overwritten (DOW1 state), as shown in FIG. 22B, both tracks on both sides of the side beam 103A and tracks on both sides of the side beam 103B are already recorded. In this case also, in the same way as that described above, the push-pull signals spp1 and spp2 of the side beam 103A and the side beam 103B have no offset, so that the main beam may not be detracked. [0018] Then, when the side beam 103A is arranged in the outer radial side than the main beam 104, a case where the L1 layer of the one side two-layered disk is recorded will be considered. In this case, the recording is executed from the outer radial side of the optical disk 100 toward the inner radial side. When recording on the white track, as shown in FIG. 23A, in both the side beam 103A and the side beam 103B, the inner radial side of the disk is the white track while the outer radial side is the recorded track. Thus, the difference between photo-acceptance amounts of the split-half light-receiving surfaces of the split-half light detector is large in the side beam 103A and the side beam 103B, so that push-pull signals spp.sub.1 and spp.sub.2 have offsets. As a result, the main beam is detracked in the white track direction, i.e., in the outer radial direction of the disk. [0019] On the other hand, in the state that the recorded track is overwritten when the L1 layer of the one side two-layered disk is recorded, as shown in FIG. 23B, both sides of the side beam 103A and the side beam 103B are recorded tracks. In this case also, in the same way as that described above, the push-pull signals spp.sub.1 and spp.sub.2 of the side beam 103A and the side beam 103B have no offset, so that the main beam may not be detracked. [0020] In such a manner, in the past system for obtaining the tracking error signal with the DPP system, when the L1 layer of the one side two-layered disk is recorded, the state that the white track is recorded (DOW0 state) other than the state the recorded track is overwritten (DOW1 state) leads to the detracking. This fact has not been reported as well as solving means therefore is not obviously reported. [0021] FIG. 24 shows example measured results of a detracking amount when the white track of the rewritable DVD is recorded. In FIG. 24, the relationship between the detracking amount (nm) and the jitter (%) during reproducing is shown for when recording from inner radial side of the disk toward the outer radial side (designated by symbol .diamond-solid. in the drawing) and for when recording from outer radial side of the disk toward the inner radial side (designated by symbol .box-solid. in the drawing). Desirable characteristics include that the most satisfactory reproducing signal (the jitter is small) is obtained when the detracking amount is zero, as shown in measured results when recording from the inner radial side toward the outer radial side. Whereas, when recording from the outer radial side toward the inner radial side, if the main beam is detracked rather in the outer radial direction, the jitter becomes smaller, obtaining favorable reproducing signals. [0022] In order to correct the detracking in such a way, under conditions in that the detracking may occur, an offset may be electrically applied to the tracking error signal. In this method, as described above, when the L1 layer of the one side two-layered disk is recorded, the detracking occurrence depends on the kind of the track to be recorded, whether it is white or recorded before. Accordingly, it needs to determine whether the track being recorded at present is white or recorded before. Continue reading... Full patent description for Disk recording apparatus, method, and recording control program Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Disk recording apparatus, method, and recording control program patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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